On the big steam engines it took a hot fire to produce all that steam. With the fire box in the back how did the fire get enough air? I would think at high speeds a vacum would form under the rear of the engine cutting off air to the bottom of the firebox. Am I missing something simple here?
Boy, I thought I would get a rise out of somebody!
I insulted all the engineers. They must all be out on runs or something.
Yes. The draft was provided by the steam exhausting from the cylinders going up the stack. This pulled air thru the fire tubes of the boiler which in turn pulled air in thru the grates in the firebox. It was a crude control system. The more steam you used in propulsion, the stronger the draft. I think it was Stephenson’s Rocket that was the 1st loco to used this system.
-Don
Actually, it wasn’t such a crude system to control the draft. The first ones of course were, but as time went on, through the use of the reverser and steam cut off the engineer could lift the coal off the grates or pull a draft so slight that the fireman would need to turn the blower on which is just another word for manually injecting steam up the stack. Mechanical engineers even found that you could shape the stack and improve the draft ie; a long oval stack and multiple nozzles.
The UP used two stacks in order to improve even heating of the water in the boiler. One stack pulled through the lower flues and the other through the upper. Many other RRs used siphons to percolate the water from the bottom of the boiler up and out over the crown sheet.
The fireman could also control the draft with a steel plate that he could open or close for more airflow. Crude really only compared to today’s computer controlled push button sit back and go for a ride engines. You could train monkeys to be engineers today!
Just yesterday I saw a UP run through town and the engineer looked like a gorilla.
Gentlemen you have been a big help. The books I have read neglected to mention that the stack created a draft air flow under the engine also.When I look at pictures of the newer steam engines and seen the smaller stack’s I assumed that they might have rigged a blower on the back end of the train. Thank you for clearing that up.
TIM A
My cousin is back in town, and as soon as he combs his back and picks the fleas off, he gonna learn to read and write, so he can say somethink back atcha!
you buffs that think that begin an engineer is sooooo easy… i would love for you to put your money where your mouth is… put you in the cab, and see how well you can take a train with “push button, sit back and injoy the ride” locomotives… start, stop, slow down for slow orders, obey all the signals, and jus down right handle the train. my moneys on you derailing or at least get a knuckel just trying to start pulling. so now… sitting at your computer or watching a train go by make you an engineer? no…i wil give yout this, power today is a lot more user friedly then the steam days… but still alot more thn just pu***he button and go…
ps, i use to fire on a steam loco so i know what it is like
LOL I knew I’d get someone.